ICU4C: Guard C++ public headers with C_SHOW_CPLUSPLUS_API

Description

Continue the discussion at ICU-20530, I provide a major cleanup without functionality change for icu public headers.

1. Remove all trailing spaces
2. Make the once macro consistent and unique and at format _U_HEADER_H_
3. Align file file prologue
4. Guard C++ using C_SHOW_CPLUSPLUS_API to allow include in C

Status

Assignee

Jeff Genovy

Reporter

Alon Bar-Lev

Labels

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Reviewer

None

Time Needed

None

Start date

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Components

Fix versions

Priority

assess